A lot of what the Mars Science Laboratory Curiosity's mission is about, is trying to discover if ancient Mars was a habitable environment, but we are also studying the current environment. Two instruments that help with that are the RAD instrument, and the REMS instrument. The RAD (Radiation Assessment Detector) measures high energy radiation coming from cosmic rays and the sun, and how it changes through the Martian atmosphere. These measurements will help understand what the environment is like on the surface, so future astronauts will know how to protect themselves from this harmful radiation.
The REMS (Rover Environmental Measurement Station) is basically the rover's weather station. It measures air pressure, humidity, temperature, wind, and more. One certain weather feature Curiosity is keeping its eye out for is a dust-devil, like the ones seen by it's ancestors, Spirit and Opportunity. Curiosity is studying the Martian surface at an interesting spot in the Gale Crater: right at the base with a 5 kilometer high mountain to the south, and a tall crater rim to the north.